The film stiffness of gas-lubricated hydrostatic bearings and seals are considered to be enhanced remarkably by proper design of a diaphragm-type restrictor. A fluid-structure coupling numerical model by coupling iteration of small deflection bending differential equation of circular thin plate and one-dimensional Reynolds equation was established, and the influence of different parameters, including pressure and geometrical parameters, on the flow output characteristics of a diaphragm-type restrictor was investigated numerically and experimentally. The results show that the correctness of established fluid-structure coupling numerical model is verified well by comparing calculated values of diaphragm deformation and output flow characteristics to the measured values. The optimum values of diaphragm thickness is 0.6–0.8 mm and initial throttle clearance is 20–35 μm for stable operation of diaphragm-type restrictor, while the optimum value of back pressure strongly depends on the diaphragm thickness.